Reducing curl of photographic film



Patented Feb. 8,1944 I UNITED STATES PATENT OFFICE 2,341,485 REDUCING CURL OF PHOTOGRAPH? FILM Donald R. Swan, Rochester, N. Y., assignor to Eastman Kodak Company, Rochester, N. Y., a corporation of New Jersey No Drawing. Application March 28, 1942, Serial No. 436,716

Claims. (01.9548) I This application relates to photography and If film so treated is to be used at high relative particularly to a method for reducing the curihumidities, such as 70-80% relative humidityv ing tendency of photographic film. the amount of urea in the treating bath should It is well known that photographic film connot be above 3.5 or 4% by weight. Film soaked sisting of a cellulosic support carrying one or 5 in a treating bath above these concentrations more emulsion layers has a tendency to curl is likely to be slightly tacky on the emulsion side when used in a photographic projector. Such at 70-80% relative humidity.

tendency is especially noticeable in the case of- In order to determine the effect of treatment 860 feet or more when used, for example, in a l I have made the followin tests on 16 il m humidity due to the alteration of the water conedges of the him away from the emulsion side. tentpf the gelatin. 20 The humidity curl amplitude is the difference It is, therefore, the object of the present inbetween curl at any two relative humidities and vention to provide a method for overcoming the may, therefore, be used as a measure of the v Curl at Humidity a water-soluble amide such as urea. 70933.11.

My invention is applicable to the treatment amplitude of photographic film consisting of a cellulosic j k support having thereon a gelatin emulsion layer -o.ooa 0.060 or layers The support may be a cellulose ester 1333? 8322 such as cellulose nitrate, cellulose acetate or -o.'o2o oIoio cellulose acetate propionate or a cellulose ether 18-3 3333 or synthetic resin The emulsion layer in which -o.'o2 o 01005 the image is formed may consist of a gelatino millimeter widths, my invention is also applicable to the treatment of sheet film or film treating solutions did not always produce a um form increase in positive or negative curl of the gg figg fig g afig i i gg gg g ii for film, the humidity curl amplitude showed a producing-the our] of j 1e d phbtogmphic m are gressive decrease, and a progressive improvement water-soluble amides such as urea, acetamide, m curling tendency'with increasing amounts formamide, malonamide, lactamide'and gluconurea amide, and mixtures of two or more of these. The following example indicates my Preferred The film is treated with these materials for a math Wet or dwpmmd motion suitable length or time such as by immersion for picture mm is immersed I01 ten minutes 1n treatment of photographic film according to my ume of the water. At the endot 10 minutes the invention is urea and I prererto use amounts m is removed, squeegeed and dried. The opranging-11pm 2% t 75% i aqueous l t eration may, of course, be carried out either as scope of the appended claims.

I-claim:

1. The method of reducing the curling tendency of finished photographic film which comprises treatingsaid film after processing with an aqueous solution containing from 2% to 1.5% of a water-soluble amide.

2. The method of reducing the curling tendency of finished photographic film which comprises treating said film after processing with a 2% to 7.5% aqueous solution of urea.

33. The method of reducing the tendency of v finished photographic film to curl when subjected to high relative humidity, which comprises immersing said film after development and fixing in a 2% to 7.5% aqueous solution of urea.

4. The method of reducing the tendency of finished photographic film to curl when subjected to high relative humidity, which comprises immersing said .film after development and fixing in a 2% to 7.5% aqueous solution of urea.

5. The method of reducing the tendency of finished photographic film to curl when subjected to high relative humidity, which comprises immersing said film for about 10 minutes in a 2% to 7.5% aqueous solution of urea and then drying said film.

DONALD R. SWAN. 

